This invention relates in general to vehicle wheels and, in particular, to an improved method for producing a rim for a vehicle wheel.
A typical sequence of steps which can be used to produce a wheel rim for a vehicle wheel is disclosed in U.S. Pat. No. 4,185,370 to Evans. As shown in this patent, the method includes the steps of: (a) providing a flat sheet of suitable material, such as aluminum or steel; (b) forming the sheet into a cylindrical hoop or band; (c) flaring the lateral edges of the hoop radially outwardly to produce a rim preform having flanges suitable for positioning on a roll forming machine; (d) subjecting the rim preform to a series of roll forming operations to produce a wheel rim having a predetermined shape; and (e) expanding the wheel rim to a produce a finished wheel rim having a predetermined circumference.
As a result of forming the wheel rim in this manner, the roll forming operations produce a rim having a generally uniform material thickness as the rim is progressively shaped. A slight thinning of the material occurs only at those portions of the rim where the curvature changes and forms a radius. Thus, the generally uniform thickness of the rim results in the rim having extra material at places where it is not required for strength purposes. Since the weight of the wheel rim affects the performance of a vehicle, it is desirable to reduce the weight of the rim.
U.S. Pat. No. 4,962,587 to Ashley, Jr. et al. discloses one method for reducing the weight of a wheel rim by thinning selected portions thereof. According to the method of this patent, a preformed wheel rim is provided having opposed finished tire bead seat retaining flanges, opposed finished tire bead seat surfaces, a well, and an axially extending inboard leg. Next, the well and adjacent rim end are mounted on a mandrel and end plate, respectively, for rotation therewith. A flow spinning roller is then actuated and advanced to engage the well and inboard leg portion thereby thinning-stretching the well and leg portions of the preformed wheel rim.
Other methods for reducing the weight of a wheel rim by thinning selected portions of the rim by rolling or pressing operations are disclosed in U.S. Pat. No. 3,347,302 to Lemmerz, U.S. Pat. No. 4,127,022 to Bosch, and U.S. Pat. No. 4,143,533 to Bosch.